Process for the treatment of iron or steel for preventing oxidation or rusting



Patented Dec. 1 4, 1926.

UNITED S ATE TE monies wa'r'rs oosnnrnaor BIR INGHAM; ENGLAND. "i-

rnoonss ronriin 'rnmrmnnr OF IRON on srnnt non nns'rma,

m; Drawing, application filed February 1526, seriaind; asses, and ew main mire 26;1925'.

c This invention relates to the treatment of iron or steel or articles composed or having a surface offiron or, steel by processes of the kind described in myprior United States patent specifications Nos. 870,937and 1,007,- 069 according towhich: theiron or steel surfacesare provided with a'protective covering or deposit ofa' compound that renders the said surfaces capable of resisting or being unafi'ected'by the action of moisture'or other oxidizing. or rusting? influences. In the processes in question the iron or steel or-the" articles composed or having a surface of iron or steel is or are subjected to the action I of adilute solution of phosphoric acid either alone or-with the addition'of asuitablei subb 'phate.

stance such as iron filings, ferrous phosphate, or a other "appropriate compound adapted to "control or regulate the chemical action upon the metal or. articles undergoing treatment, or of phosphoric acid inthe presence ofzi-nc' or a suitable zinc compound, or of a solution thereof in phosphoric acid,- or" of a solution of acid zinc phosphate (that is zinc phosphate solution with asmall excess offphosplioric acid), or of a solution containing zinc phosphate and iron phos- 'According to the present'inventioii a process of the kind referred to for the treatment or articles with an iron or' steel surface'consis'ts in subjecting it or'them to the action of a solution of one'orother of the kinds lie'reinbet'ore referred to and containing as an additional constituent a compound of boroinyfor instance boric'acid or a. borate such for'example as .borax, care being exercised, to select a boroncompound such as" will not detrimcntally affect -the deposit on the 'iron or'steel. Preferably the solutions employed for the present process should be only slightly acid; as an illus tr'ati'o'n it 'may bementioned that a suitable aci dity of a bathot zinc phospl'iate solution, before the addition of the'boric acid thereto; is such that 10 cubic centimetres of the solution require about 4.8 to5.5 cubic centimetres of'deci-nornial sodium hydroxf ralizatiou.

-For the treatment of articles by the improved process accordingto the present invention there may be taken as an example of a suitable bath solution one prepared by dissolving pasty or concentrated-acid zinc ph'ospl'iate and boric acid (powdered or crys- "centrated,

solution is of a bath of zinc phosphate sol 'tals) in'water in the approximate relative rnnvnnrme oxrnn'i'ro'n on" proportions of about 2 ouncesofthephos phate and 1 lon ofwater; [I

Forthe preparation of the'pasty or conacid zinc phosphate a suitable method is I lated 'or' powdered zinc" in pint phos phoric; acid B. P. and pint hot Waterthe solution is set'aside" for a few hours, stirred; andapasty or powdered mass suitable for use in making up'thebath solution in the proportions previously mentioned is obtained.-'

The treatment'of the iron or steel-orarti-i cles with'an iron or steel 'surfaceis ably carried outwith a hot solution order to diminish prefer- 7 loss of boric acid therefrom due to its -volatility in steam, thevessel' in which it is contained and wherein the treatment of, the iron or steel articles is carried out should be kept covered as'm'uch as possible so as to reduce evaporationto a minimum. To the concentration of boric acid present" in the bath solution during the treatment 010-: eration an additional amount of boric acid maybe added from timetotiine-so as to compensate for that lost by evaporation and keep the'amount ofboric acid in the solution as constant as-possible. of the solution when required 'maylalsobe added to the bath; from time to tim to replace those used up in carrying out the process. i

A suitable method for determining the approximate quantities of acid zinc phosphate and'boric acid I as follows: 10 cubic centimetres of thebath solution are titrated'with a deci-,- normal solution of sodium hydroxide using phenolpthalein as anin'dicator. i The fresh bath prepared with the qua'ntitiesof acid zinc phosphate and boric acid mentioned above requires about 6.5 to 7 cubic centimetres of theasodium hydroxide soluti'om the increase ot'abdut'l to 1.5 cubic centimetres over the titration'fig ure obtained in the case ution alone being due to the presence of the boric acid. After reading the burette there is added to the vessel containing the rose colouredsolu tionabout 30 cubic centimetres of a neutralized calcium chloride solution "prepared by dissolvingabout grammes-of calcium containedin the bath unces bori acid toone gal? to dissolve 6 ounces finely granuand in I 9 Otheriingredients. 7

then again run in which a perio chloride in 150 cubic centimetres of water, whereupon the "rose colour will be discharged. The sodium hydroxide solution is from the burette until'the rose colour reappears and remains perma nent after a thorough shaking. In the case of the freshbath solution about a further '13 cubic centimetres of the deci-normal sodium hydroxide solution will be required, thus making. a forthe two'titrations. The first titration figure obtained, aftermaking an allowance of aboutlto 1.5 cubic centimetres-forthe boricv acid present, measures approximately the amount of acid fzinc I and'the second figure obtained (13 cubic centimetres for the fresh bath) measures approximately the amount-of-borie acid pres--' .ent. By titrating a sample portion of the bath in this manner the quantities of acid zinc phosphate and boric acid and from the results obtained the desired quantities of ingredients canbe added to the bath solutionwhennecessary to renew 1- its strength.

Before. treating the articles inthe solution they may previously be immersed for a short period, say a few minutes, in a hot orcold solution of boric acid of about five per cent or. less concentration.

The articles to betreated may be suspended in the solution on iron or zinc wires or on holders or'in containers made of any suitable material. that has no detrimental effect on the solution,

The formation of the deposit on, the ironor steel or surface current through the solution; when this procedure is a apted a cathode ofzinc, iron or steel should-be employed and the article to be treated should be made the anode, 7

By the use of a solution containing boric acid or a .borate in accordance withthe resent invention the uniformity andad erence of the deposit obtained on the iron or steel arev much enhanced, and the treatment is rendered very much more rapid as deposits can be obtained in a fewminutes which are even more effective for rendering the surface of the article treated non-oxidiz roof than the 'deposits for of about 1 hours" treatment able or rustwas required .with the solutions heretofore employed. Further considerable saving results from the process owing, to deposits of the desired character being obtained in much less time and with much. less depletion of the constituents. of the solution than was hitherto. ssible. 5

What claim anddesire to secure by Letters Patent of the United: States is 1'.;A process of the kind referred to for the treatment of total-of 20 cubic. centimetres phosphate present,

present. at any time can be'approximately ascertained p phoric acid of under treatment may be iron or steel or articles.

steel which consists in subjecting the same to the action of an aqueous solution of acid zinGphosphate and boric acid in the relative proportions of about two ounces of'the phosphate and one and'one thirdounces of the boric .acid to one gallon of water, for the purpose specified.

2. A process for the treatment of iron or steel or articles surface of iron or steel for preventing the oxidation or rusting in subjecting the same to the action of solution of phosphoric acid and a compound of boron. I

3. A process fort steel or articles composed or having a surface of'iron or steel for preventing the oxidation or rusting thereof which consists in subjecting the same to the action of,a zinc-containing and boron-containing;solution of'phos horic'acid. I

4. A process for the treatment of iron or steel or articles composed or having a surface or rusting thereof, which consists in subjectcomposed or having a re treatment of iron or mg ,thesame to the action of a dilute zinc-j containing and 1 boron-contalning solution I of phosphoric acid. 1 I

A process for the treatment of iron or steel-or'articles composed or having a surface of iron or steel for or rusting thereof ing thjefsame to the action of mgand boron-containing solution of phostration.

6. A process steel or articles'compose' of ironorpsteel or rusting thereof whi ingthe same to the actionof a' solution of hosphoric acid and a with the addition of a. substance iadaptedto control or regulate the chemical reactions.

- "7. A process of iron or steel preventing the oxidation which cons sts nsub ecta zinc-containcan varying degrecsof concenfor the treatment of iron or i v dor having a surface for preventing the oxidation 1"" h consists in'subjectcompound of boron for the treatment of iron or 1 steel or articles composed or having a surface for preventlng the oxidatlon or rusting thereof, which consists in subject- 'ing the same to the action of a dilute soluv tion ofphosphoric acid and a compound-of 1 boron with the additionof a substance adapted to control or regulate the chemical ,re-. actions.

' -8. A process forthe treatment of iron or steel or articles composed or having a surface of iron or. steel which consists in subject or rusting thereof the actlon of ,a solution *ing the same to containingxzinc and iron phosphate and .a compound of boron.-

the treatment of iron .or

9. A process .for steel or artlcles composed or having a surface of ron or steel for preventing the oxidation por rusting thereof, which consists in subject" for preventing the oxidation.

. of iron or steel for preventing the oxidation or rusting thereof which consists in' sub ect-v ting the same ,totlie action of a dilute solu 10. A process for the treatment of iron steel or articles composed or having a' surface ing the same to the action of a dilute solu- "tion. of

boron. i

11. A process for the treatment of iron or steel or articles, composed or having a surface of iron or steel for preventin the oxidation or rusting thereof which consists in subject-- ing the same to. the action'of a zinc-conta1ning and boric-a cid-containing. solution of phosphoric acid.

12. A process for'the'treatment ofiron or steel or articles composed or having a surface of iron or steel for preventing the oxidation or rusting thereof which consists in subjecting the same to the action of a solution of phosphoriciacid and-boric acid the addition of a substance adapted to control or regulate the chemicalreactions. 13. A process for the treatment of iron" or steel or articles composed or having a surface of iron. or steel for preventing the oxidation or rusting thereof, which consists in subject- 0 ing the: same to the action of a-dilutej soluv or rusting thereof which consists in subjecting the same to the action of a dilute solu v tion of phosphoric acid and -boric acid with.

the addition'o'f a subdance adapted to control or regulate the chemical reactions.

' 14. A process for the treatment of iron or steel or articles com-posed or having a surface; I

vtion duringthe treatmenttherewith of-the iron or steel or articles with an iron or steel of iron .or steel for preventing the oxidation ing the same to the, action of a, solution containing zinc and iron phosphate and boric acid. I

15. A process for the treatment. of iron or 1 steel or articles composed or having a surface of iron or steel for'preventing the oxidation or rusting thereof which consists in sub ecting the same to the action of a dilute solution containing'zinc and iron phosphate and boric acid.' v I 1.6. A process for the treatment of iron or,

1 steel or articles composed or having a surface of iron or steel for-preventing the oxidation or rusting thereof which consists in subjecttion of phosphoric 'acid and boric acid.

17 A process for the treatment ofiron or steel or articles composed or having a surface of iron or steel for preventing the oxidation or rusting thereof which consists in subjecting the same to the action of a solution containing acid zinc phosphate and boric acid in or about the proportions hereinbefore statedl i 18 A process fore subjecting the articles to the treatment 'with thesolutionthey are immersed forla short period in a solution of boricv acid.

phosphoric acid and a compound ofv g fore-subjectinglthe articles to the treatment" withflthe solution-they are immersed for a short period in a solution of boric acid.'

with the solution they are, immersed'for a electric current is passed through-thesolution during thetreatment'therewith of the I iron or steel or articles with an iron or steel a surface for thepurpose specified. 27. A process as in claim 2, in whichan tion during the treatment therewith of the iron or steel .or articles-with an iron or steel as in claim 1, in which be- 19. A -ea. as in claim 2, in which be fore subjecting the articles to the treatmentwith the-solution they are immersed. for 'a- 1 shortperiod in a solutionof borioacid.

21, A process as in claim'.-.6, in which be-.

22. A process as claim 8, in whichjbe. 'fore'subjecting the articles to the treatmentshort period in asolutionof borioacid;

23. A process as in claim 10, inwhichbe fore sub ecting the articles to the treatment with the solutlon-they' are-*immersedfor" a short period in a solution of boric acid.

24. A process as in claim 13, in which beforesubje'cting the articles to the treatment with the solution they are immersed'for a; f

short period in a solution of boric acid.-

' 25. 'Aprocessas inflclaim 14, in which before; subjecting :the articles to the treatmentwith the solution they are immersed for a short period in a solutionof boric acid. I 26. A process as in claim 1, in which an electric currentds .passed through thesolusurface for the'purpose specified.

iron or steel or articles with an iron or steel surface for the purpose specified.

29. A process as in claim 14-, in which an electric current is passed'through the S0111? surface ,for' the purpose specified.

'30., In' the treatment of iron or steel" or 'l5 olution of ,phosphoric articlescomposed of iron or steel a compound consisting of a dilute s acid and 21 compound of boron. v

81. [In-the treatment of'iron orj steel"v or articles composed of iron or steel a compound consistngof a zinc-containing and boron-"- Cbntaini'ngsdution of phosphoric acid.

32. In the treatment of iron or steel or.

. articles composed of iron or steel a compound I consisting of a solution containing zinc and iron phosphate and a compound of boron.

' 33. In the treatment of iron or steel or articles composed of iron or steel a compound consisting of-a solution containing acidlzino phosphate and boric'acid.

28. A-process as in claim 10,1 which an THOMAS" WATTS Cosme. v 

